1. Technical Field
The present invention relates to an imaging lens and an imaging device and, more particularly, to both an imaging lens suited for use in a vehicle-mounted camera, a portable terminal camera, a monitoring camera or a on-board camera using an imaging element of CCD (Charge Coupled Device), CMOS(Complementary Metal Oxide Semiconductor) or the like, and an imaging device having the imaging lens.
2. Related Art
In recent years, the imaging device of the CCD or CMOS is remarkably advancing in size reduction and in high pixel density. Accordingly, the imaging device body having those imaging elements is being reduced in size so that the imaging lens to be mounted is desired to be reduced in size and weight.
In the vehicle mounted camera or the monitoring camera, on the other hand, there has been demanded a lens which can be used over a wide temperature range while having high weather resistances to the ambient air in a cold country to a vehicle compartment in summer in the tropical districts and which is small-sized but can enjoy a wide angle and high performances.
As the imaging lens of the aforementioned field, the Applicant has proposed the imaging lenses having six and seven lens components while intending the size reduction and the angle widening in Japanese Patent Application Number 2007-011288 (not yet published). The imaging lenses known in the prior art and belonging to the aforementioned field are described in the following Patent Documents 1 to 3. Patent Document 1 (U.S. Pat. No. 7,023,628) described a wide-angle lens of six lens components having first and second negative meniscus lenses. Patent Document 2 (JP Hei. 10-039206 A) described an imaging lens of five components having negative first and second lenses and a diaphragm arranged on the image side farther from the lens closest to the image. Patent Document 3 (U.S. Pat. No. 4,525,038) describes a wide-angle lens of five lens components and for use in a photographic system.
In recent years, however, not only the further size reduction but also the cost reduction is desired, and the aforementioned constitutions of six and seven components are desired to reduce the lens number. The lens constitution described in Patent Document 2 is composed of five lenses, but the diaphragm position is close to the image plane so that the light ray height in the lens on the side closest to the object increases to enlarge the lens diameter. Especially in the vehicle-mounted camera, it is preferred that the exposure area of the lens surface is small, and accordingly that the diameter is small.
In view of the aforementioned described, the present invention has an object to provide an imaging lens which can be reduced in size and cost while holding the satisfactory optical performances, and an imaging device having that imaging lens.